Achieving the Maximum: Estimating Energy Savings

In September 2017, the DesignLights Consortium (DLC) published “Energy Savings from Networked Lighting Control Systems.” The report analyzes the energy-savings potential of networked lighting control systems. Based on aggregate data from more than 100 installations, the report found an average of 47 percent lighting energy savings.

Networked lighting controls enable devices to communicate and enact control strategies. As utilities and energy-efficiency programs seek to increase energy savings, they are incorporating this technology in their rebate programs. In support, the DLC launched a market transformation program that developed a specification for networked lighting control systems, resulting in a Qualified Products List (QPL) for networked lighting controls and, coming spring 2018, contractor training.

In 2017, more than 20 rebate programs launched incentives designed to promote networked lighting controls listed on the QPL. An inhibitor to broader implementation has been reliable estimates of energy savings. Most studies either relied on small sample sizes or were based on older technology. To address this, the DLC conducted a study to help better quantify the value of networked controls.

“This study provides energy-­savings estimates that both end-users and industry decision-makers can use,” said Gabe Arnold, DLC technical director. “It supports the development of more networked lighting control utility programs that provide critical incentives to reduce first cost. And, we believe the data guidelines will help standardize data collection efforts going forward.”

Conducted by Energy Solutions, the study analyzed hourly energy monitoring data from more than 1,200 zones in 114 commercial buildings. Actual energy use was compared to estimated energy use if the lights had been on at full output during occupied hours. This avoided monitoring to establish a baseline, produced granular data (by hour and zone), and isolated control savings from lighting savings produced by an LED retrofit.

The standardization of data reporting allows for apples-to-apples comparisons of energy consumption between buildings and space types. It also enables utilities to require monitoring data as a rebate requirement, which would be prohibitive to manufacturers if they all required different reporting formats.

urrently, manufacturers vary in how they measure and report energy data; a unified utility requirement may promote standardization among their systems, further promoting technology adoption.

The DLC found an average of 47 percent energy savings from networked lighting controls, excluding additional savings from a luminaire retrofit. (This means, after new LED lighting was installed, the energy use of that LED lighting was reduced by 47 percent on average if controlled by a networked lighting control system.) Roughly 70 percent of the projects achieved savings of 30 percent or more, and 30 percent achieved savings of 70 percent or more.

Energy savings varied widely across the buildings, with a range of 2 to 91 percent. Aside from warehouses, which consistently showed greater than 75 percent energy savings, the type of building had little influence on savings. The variance was more dependent on type of space and its characteristics.

“While we had limited insight into the operational characteristics of each building, it appears sites with lower energy savings were using their networked lighting control system primarily as a scheduling control,” Arnold said. “Buildings with high energy savings represent the potential of networked lighting controls when implemented with multiple strategies, aggressive settings, beneficial site characteristics, occupancy patterns, and/or user behavior. In the highest-performing sites, a combination of aggressive high-end trim and occupancy sensing were likely the major factors contributing to the high savings results.”

The DLC is planning a follow-up study that will add more buildings and project information to the database. The hope is to explore questions such as what specific site and building characteristics drive energy savings, which control strategies produce the highest savings, and the relationship between configured settings and energy savings. This may contribute to greater certainty in predicting energy savings for a given building and to the development of best practices.

For now, ECs can use the study results to communicate average networked lighting control energy savings to their customers, produced by a credible third party. Maximizing energy savings entails exploring the system’s full feature set and implementing the full range of strategies with more aggressive configuration settings. Utilities and energy efficiency programs, meanwhile, will use the study results to justify rebates ECs can access to reduce first cost.

“The DLC report will give end-users a better understanding of the average savings they can expect from networked lighting control technology, reducing the risk of using the systems,” Arnold said. “The report does reinforce that lighting control savings vary widely, and therefore, end-users should work with their installer and industry professionals to ensure they achieve maximum energy savings on their project.”

Download the DLC’s “Energy Savings from Networked Lighting Control Systems” at www.designlights.org.

About the Author

Craig DiLouie

Lighting Columnist
Craig DiLouie, L.C., is a journalist and educator specializing in the lighting industry. Learn more at ZINGinc.com and LightNOWblog.com .​

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